At present, disks used in hard drive media frequently include an aluminum-magnesium (AlMg) substrate that is plated with materials, such as nickel-phosphorous (NiP), which provide a smooth surface on which to deposit magnetic recording layers used to store data. In order to increase data storage space, hard disk drives may utilize technologies such as EAMR (Energy Assisted Magnetic Recording), which require magnetic recording layers with high magnetic anisotropy (Ku). Often, such high magnetic anisotropy magnetic recording layers include alloys that require deposition temperatures in excess of 300° C. (e.g., Fe, Pt, Sm and Co). However, the NiP coating currently used to provide the magnetic recording layer in disk media (e.g., EAMR media) with its smooth surface cannot withstand temperatures in excess of 300° C., at least not without dramatically increasing the magnetic recording layer's surface roughness.
Fortunately, hard drive disks have been developed where the substrate comprises an alloy of aluminum (Al), and a coating layer designed to support high thermal stability during high sputtering temperatures (e.g., greater than 300° C.). The coating layer for the developed disk comprises Ni, X1 and X2, wherein X1, comprises one or more elements selected from the group consisting of Ag, Au, B, Cr, Cu, Ga, In, Mn, Mo, Nb, Pb, Sb, Se, Sn, Te, W, Zn, and Zr, and wherein X2 comprises either B or P. Typically, the coating layer is applied to the disk through an electroless plating process, which is eventually followed by a polishing process to increase the smoothness of the resulting disk surface before deposition of the magnetic recording layer. It has been shown that polished AlMg/Ni—X1—X2 disks exhibit higher thermal stability when compared to conventional NiP-coated AlMg disks.
FIG. 1 is a diagram illustrating an example disk 100 comprising an aluminum (Al) alloy substrate 101, and a Ni—X1—X2 coating layer 103. The coating layer 103 is disposed over the substrate 101 and comprises an alloy of Ni, X1 and X2. Depending on the implementation, the coating layer 103 may be between about 1 and 20 μm in thickness. Disk 100 further comprises a zincate layer 102 disposed between substrate 101 and coating layer 103, which helps prevent the aluminum substrate 101 from oxidizing. At the top of disk 100 is the magnetic recording layer 104, which, as discussed above, may comprise a material, such as Fe, Pt, Sm and Co, requiring a high temperature (e.g., over 300° C.) deposition process to be applied to the disk.